Abstract: Rhizobium radiobacte WSH2601 was mutagenized by using UV-radiation and NTG mutation consecutively. An actinomycin-D resistant mutant, R. radiobacte WSH-F06, was isolated after two runs of screening. The CoQ10 yield of mutant WSH-F06 increased by 16% compared to that of the parent strain. The effects of nutritional and environmental conditions on the production of CoQ10 by R. radiobacte WSH-F06 were investigated in shaking flasks. A complex carbon source consisting of glucose (30 g/L) and molasses (60 g/L) was shown to be suitable. In addition, R. radiobacter WSH-F06 could assimilate a variety of nitrogen sources, including organic and inorganic nitrogen compounds. A compound nitrogen source consisting of (NH4)2SO4 (7 g/L), peptone (5 g/L), yeast extract (5 g/L), corn steep liquor (30 g/L) was developed by using orthogonal experiments. The inoculum size had no obvious effect on CoQ10 fermentation. The optimum initial pH for CoQ10 fermentation was 7.2, while the optimum volume of medium (medium volume vs. flask volume ) was 50 mL/500 mL. Under the optimized fermentation conditions, the CoQ10 yield and the intracellular CoQ10 content reached 34 mg/L and 2.4 mg/g, which were 2.6- and 1.1-fold higher than that of the parent strain under the original conditions, respectively.

Key words: Rhizobium radiobacter, coenzyme Q10, mutation, fermentation

摘要： 以放射型根瘤菌(Rhizobium radiobacter)WSH2601为出发菌株，经紫外线和亚硝基胍复合诱变，获得遗传稳定性好的抗放线菌素D突变株WSH-F06. 在摇瓶中考察了碳、氮源等营养条件以及接种量、装液量和初始pH等环境条件对突变株WSH-F06细胞生长和积累辅酶Q10的影响. 通过诱变和优化发酵条件，突变株WSH-F06的辅酶Q10产量和胞内含量分别达到34 mg/L和2.4 mg/g，比出发菌株在同样条件下提高了16%.

关键词: 放射型根瘤菌, 辅酶Q10, 诱变, 发酵条件优化